Clustering involves organizing objects into different groups based on characteristics of the objects. Clustering processes can be used in a variety of applications. One application for clustering includes building a search index, which could be used to provide search results that relate to a user's geographic location (e.g., a list of businesses in a user's zip code). The clustering process may identify records describing a particular entity and merge those records together as a cluster representing that entity. The clusters can then be used to generate listings in the search index, where each listing represents a cluster of different records associated with the same entity.